Abstract: As one of Carson McCullers's masterpieces,The Ballad of the Sad Cafédepicts a complicated story of triangular love,in which both extreme love and hatred are involved with the revelation of absurdity in human nature. As far as the author's experiences are concerned,existentialism plays a vital role in Carson's life as well as her writings that can not be neglected by any critics and readers.On one hand, Carson McCullers made great achievements in literature by applying existentialism to dissolve physical and emotional predicaments. On the other hand, this philosophy is employed to interpret the truth of love and hatred which is covered with an apparently simple plot. By analyzing the inexplicable relationship between the characters and the personality of Amelia,the heroine,in the existentialist context,the profound insight into humanity and existence is fully demonstrated.